Install:
I used 80sqft (1 layer) of this product all over my car doors, inner doors, floor, ceiling, and rear wall. When I bought it I figured 80sqft would be more than enough. However, I actually ran out of it. I could have used another 20sqft to finish the inner doors and back wall. Installation was very time consuming. It took me 4-5 days to get all of it installed. Most of the time was the preparation work. Before you install the sound dampening you must use paint thinner to clean off all the dirt, grease, stickers, and anything else that could affect the performance of the product. Actually installing the product was very simple. Anyways, when you install it you lay down one end of the material. Then, push from deepest part of the application surface out to the shallower parts. The foil crimples but that's not a big deal. Anyways, it's very helpful to mark the holes in the metal as you're covering it. You can use a tooth pick or just make a slit with the razor blade. After you're done cut out the holes out, then use the roller to make sure that the material touching as much of the surface as possible. I used a roller I purchased from home depot in the carpet. The roller was about 3 bucks and was good enough for the job. One piece of advice is wear painting clothes while installing it. The asphalt is very hard to get out of your clothes.

Performance (installed on doors only):
I can only give a performance review with it only on the doors. When I installed it everywhere else I put vinyl liner on top of it.

It improved the midbass, eliminated all the rattling where it was installed, and dampened road noise a little. It was quieter but much of road noise was getting through the other parts of the car. If you're looking to make your car quite it takes a lot more than just the doors to affect road noise drastically. However, I couldn't hear road noise coming from the doors as much as I used to. Anyways, it was still well worth the money.

Comments:
This product is well worth the money. It can withstand almost 500 degrees of heat. That's way more than dynamat. I wouldn't use another sound dampening product in my engine compartment. It'll eliminate all the rattles a sub can make. It'll make you're car a lot cooler after sitting in the sun for hours. If installed everywhere, it'll dampen road noise drastically. The install is time consuming but it's worth it.